Why not wait until next halving to put funds in?

My friend and I are both math nerds and they were asking about how Bitcoin works. I explained as much as I could in the 25 minutes they were available to talk during their lunch break. They asked a question I seem to have never thought of for some reason:

If Bitcoin pumps shortly after every halving, why not wait until the next halving (May 2024) to put any funds into Bitcoin?

I could not answer this one, except to suggest that it does not hurt to dollar cost average into Bitcoin as that is how the safer person would do things.